Thin Film Transistor Liquid Crystal Displays (TFT-LCDs) as a kind of flat panel display devices are more and more applied in the field of high performance display because they have advantages of small volume, low power consumption, radiation-free, relatively low production cost, etc.
A TFT-LCD comprises an array substrate and a color filter substrate. A liquid crystal layer is provided between the array substrate and the color filter substrate, the intensity of light passing though the liquid crystal layer is controlled by means of controlling deflection of liquid crystal molecules, and then, color image display is realized with the aid of filter action of the color filter substrate. For the sake of realizing the effective control of deflected liquid crystal molecules, it is necessary to provide alignment layers on the array substrate and the color filter substrate, respectively, and then to fabricate alignment grooves in a same direction at a surface of each alignment layer by a rubbing process, so that liquid crystal molecules situated in the alignment grooves are aligned in the same direction.
As there is a step on the array substrate and/or the color filter substrate in the rubbing direction, different deformed zones are generated at a surface of a rubbing cloth on a rubbing roller. In addition, because frictional strengths of different deformed zones are non-uniform, alignment grooves fabricated during the rubbing process are non-uniform in depth. Accordingly, an undesirable phenomenon with lump grayscale non-uniformity caused by the above defects in alignment (referred as Rubbing Mura) occurs during display.
In addition, in order to take control of the image display of the display panel of TFT-LCD, a driving IC (Integrated Circuit) is required to be bonded to a bonding region of the display panel. Generally, during such bonding process, a via hole needs to be provided at the bonding region of the display panel, so that a lead wire in the bonding region is connected to a gate line or a data line in a display region, and then control signals output from the driving IC are input to the data line and the gate line.
Because some thin film layers at the via hole are removed, there is a step between the via hole and its surrounding region. As a result, the planarity of the surface to be rubbed is degraded; and then, during the alignment process, the alignment grooves are fabricated to be non-uniform in depth, giving rising to generation of Rubbing Mura. Thus, display effects of the display panel and quality of products are greatly reduced.